The mechanics of seed-dispersion in Ricinus communis 
J. B. DanpDENo 
Seed-dispersion is a matter of such common knowledge that 
almost everybody has had some experience with some special 
adaptation exhibited by certain plants, one way or another. The 
more common agents which serve the plant’s purpose are wind, 
water and animals. But there are various other means, not so 
apparent, and consequently not so well known, which contribute 
towards the well-being of the plant in its struggle for space (or 
room) in which to flourish. 
One method, not so uncommon as is generally supposed, is 
here examined in some detail with a view towards gaining some 
definite knowledge in regard to the actual dynamics involved in the 
Projection of the fruit. To illustrate this problem the castor bean 
was selected. 
The advantage to a plant of some special means of transport- 
ing its seed is so apparent that it needs no comment. How the 
plant came to possess this special means, is a question which largely 
belongs to the problem of evolution, and is not here discussed. 
To understand the whole question fully it is necessary to ex- 
amine all the conditions. ach plant of the castor bean produces 
on an average about five flower-clusters, the axis of each cluster 
being nearly perpendicular to the ground. On each cluster there 
are about fifty-eight fruits, each borne ona peduncle which inclines 
about forty-five degrees to the vertical. The axis of each fruit is 
at right angles (approximately) with the peduncle and inclining to- 
wards the ground at an angle, therefore, of forty-five degrees with 
the vertical. At this angle, one of the fruit-parts (carpels) would 
be projected at an angle of forty-five degrees above the horizontal 
(theoretically the angle of projection which produces the greatest 
range). But, as the carpels commence to separate, they do so 
from the dase of the fruit, thereby lessening the angle of that one 
carpel some five or ten degrees ; and, since atmospheric conditions 
have to be taken into account, forty degrees is the angle which 
gives actually the greatest range, so it is easy to see that the plant 
as the best actual position to project its seed to the greatest 
